Single package wireless communication device

ABSTRACT

An integrated circuit package includes a substrate, first, second and third dies and an antenna. The substrate includes a first layer with electrical traces and a second layer substantially formed of a dielectric material. The first die includes a first integrated circuit. The second die includes a second integrated circuit electrically coupled through wire bonds to the integrated circuit on the substrate and mechanically coupled to the first die such that the first die is disposed between the substrate and the second die. The third die includes a third integrated circuit and is electrically coupled to the integrated circuit on the substrate. The antenna and the first, second and third integrated circuits substantially form a radio transceiver.

TECHNICAL FIELD

The invention relates to the field of microelectronics and more particularly, but not exclusively, to packaging wireless communications devices.

BACKGROUND

The evolution of integrated circuit designs has resulted in higher operating frequency, increased numbers of transistors, and physically smaller devices. This continuing trend has generated ever increasing area densities of integrated circuits and electrical connections. The trend has also resulted in higher packing densities of components on printed circuit boards and a constrained design space within which system designers may find suitable solutions. Physically smaller devices have also become increasingly mobile.

At the same time, wireless communication standards have proliferated as has the requirement that mobile devices remain networked. Consequently, many mobile devices include a radio transceiver capable of communicating according to one or more of a multitude of communication standards. Each different wireless communication standard serves a different type of network. For example, a personal area network (PAN), such as Blue Tooth (BT), wirelessly maintains device connectivity over a range of several feet. A separate wireless standard, such as IEEE 802.11a/b/g (Wi-Fi), maintains device connectivity over a local area network (LAN) that ranges from several feet to several tens of feet.

A typical radio transceiver includes several functional blocks spread among several integrated circuit packages. Further, separate packages often each contain an integrated circuit designed for a separate purpose and fabricated using a different process than that for the integrated circuit of neighboring packages. For example, one integrated circuit may be largely for processing an analog signal while another may largely be for computationally intense processing of a digital signal. The fabrication process of each integrated circuit usually depends on the desired functionality of the integrated circuit, for example, an analog circuit generally is formed from a process that differs from that used to fabricate a computationally intense digital circuit. Further, isolating the various circuits from one another to prevent electromagnetic interference may often be a goal of the designer. Thus, the various functional blocks of a typical radio transceiver are often spread among several die packaged separately.

Each package has a multitude of power, ground, and signal connections which affects package placement relative to one another. Generally, increasing the number of electrical connections on a package increases the area surrounding the package where trace routing density does not allow for placement of other packages. Thus, spreading functional blocks among several packages limits the diminishment in physical size of the radio transceiver, which in turn limits the physical size of the device in which the radio transceiver is integrated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a prior art radio transceiver application.

FIG. 2 illustrates a block diagram of an exemplary single package radio transceiver application.

FIG. 3 illustrates a cross-sectional view of an exemplary single package radio transceiver.

FIG. 4 illustrates (1) an exemplary array of solder balls for coupling a single package radio transceiver to a printed circuit board and (2) an exemplary array of solder pads on a printed circuit board to which a single package radio transceiver may be coupled.

FIG. 5 illustrates an embodiment of a method of packaging a single package radio transceiver.

FIG. 6 illustrates a system schematic that incorporates an embodiment of a single package radio transceiver.

DETAILED DESCRIPTION

Herein disclosed are a package, a method of packaging, and a system including the package for an integrated, multi-die radio transceiver.

In the following detailed description, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. Other embodiments may be utilized, and structural or logical changes may be made, without departing from the intended scope of the embodiments presented. It should also be noted that directions and references (e.g., up, down, top, bottom, primary side, backside, etc.) may be used to facilitate the discussion of the drawings and are not intended to restrict the application of the embodiments of this invention. Therefore, the following detailed description is not to be taken in a limiting sense and the scope of the embodiments of the present invention is defined by the appended claims and their equivalents.

Description of a Radio Transceiver

Please refer to FIG. 1 for a functional block diagram of a typical prior art radio transceiver application.

A typical radio transceiver usually includes several separate functional blocks, including a Front End Module (FEM) 106, a Radio Frequency Integrated Circuit (RFIC) 108, and a Base Band/Communication Processor 112, that electrically couple to application specific circuitry 118. The typical radio transceiver spreads the several functional blocks among different die and integrated circuit packages. The FEM 106 generally processes a radio frequency (RF) signal collected from an antenna 104. The FEM 106 may include a low noise amplifier for small signal receiver gain larger than about 90 dB or a power amplifier for output power in excess of about 17 dBm or about 50 mW, and passive frequency selection circuits. The FEM 106 processes the RF signal before communicating a signal to the RFIC 108 for mixed signal processing. The RFIC 108 usually converts the RF signal from the FEM 106 to a digital signal and passes the digital signal to a Base Band/Communication Processor 112. The Base Band/Communication Processor 112 generally communicates with application specific circuitry 118 that often includes an application processor 122 coupled to user interface peripherals 126 and a system memory 120. In some instances, the Base Band/Communication Processor 112 is coupled to a memory 110 which may be on a separate die, or integrated into the die of the Base Band/Communication Processor 112. Power consumption for the application processor may be managed by power management circuitry 124. The RFIC 108 may also receive a signal input gathered from a Global Positioning System Receiver (GPS Receiver) 114.

The FEM 106 and RFIC 108 are often on different die because of functional differences between the circuits that may not be easily achieved through the same die fabrication process. The Base Band/Communication Processor 112 may typically perform computationally intensive operations and therefore be fabricated using yet another process that differs from either of those used to fabricate the FEM 106 or the RFIC 108. Further, the different die will often be packaged separately, although some prior art radio transceivers have integrated the FEM 106 and RFIC 108 within the same package, as indicated by the Prior Art Wireless Integration block 102. Usually, the GPS Receiver 114 will also be packaged separately from other die. Further, the reference oscillator (crystal) 116 will generally be in a different package due to its sensitivity to temperature variance.

Current packages that integrate the FEM 106 and RFIC 108 use arrays of solder bumps on the individual die to couple the die to a package substrate. Further, the die are each disposed on the substrate in a substantially two-dimensional layout. A radio frequency transceiver integrated in a single package may address many shortcomings of present radio frequency transceivers. Because the different die will often be packaged separately, current system costs will often be higher than if the various die could be included in a single package. Further, because present systems continue to evolve to smaller form factors, a radio frequency transceiver integrated into a single package may help a system designer to achieve a desired overall system size that by itself is smaller than a radio frequency transceiver spread among several packages.

Integration of a Radio Transceiver in a Single Package

FIG. 2 illustrates a functional block diagram of a system 200 using a radio frequency transceiver 202 wherein the radio frequency transceiver 202 is integrated into a single integrated circuit package, shown as 300 in FIG. 3 and further described below. The radio frequency transceiver 202 includes an antenna 204, an FEM (analog) 206, an RFIC (mixed analog/digital) 208, and a Base Band/Communication Processor (digital) 212. The reference oscillator (crystal) 216 resides outside the integrated circuit package 300 because of its sensitivity to temperature and mechanical stress, both of which are often unavoidable during package assembly. Some embodiments of the radio frequency transceiver 202 also include a memory 210 coupled to the Base Band/Communication Processor 212. Other embodiments of the radio frequency transceiver 202 may be capable of receiving input from other types of receivers, for example, a global positioning system receiver 214. The signal collected by the alternative receiver 214 is transmitted to the RFIC 208. The digital output of the Base Band/Communication Processor 212 couples to an application specific integrated circuit 218 that includes an application processor 222. Further, the application processor 222 couples to a memory 220, power management circuitry 224, and any peripherals 226. The peripherals 226 often include one or more of the following: an input/output interface, a user interface, an audio, a video, and an audio/video interface.

The application processor 222 often defines the standard used by the radio frequency transceiver 202. Exemplary standards may include, by way of example and not limitation, a definition for a personal area network (PAN), such as Blue Tooth (BT), that wirelessly maintains device connectivity over a range of several feet, a local area network (LAN) that ranges from several feet to several tens of feet such as IEEE 802.11a/b/g (Wi-Fi), a metropolitan area network (MAN) such as (Wi-Max), and a wide area network (WAN), for example a cellular network.

An exemplary embodiment of a package 300 that integrates a radio frequency transceiver 202 is illustrated by FIG. 3 and utilizes die stacking, or packaging in a third dimension, to alleviate many of the aforementioned problems, such as limited diminishment in size and increased packaging costs, associated with prior art two-dimensional layouts. The integrated radio frequency transceiver 202 in a single package 300 includes an antenna 204 formed by a copper stud 322 and a stack of a first die 306 and a second die 310 coupled to the package substrate 328, to which is also coupled a third die 302.

In the embodiment of FIG. 3, the third die 302 forms a front end module 206 and is coupled to the substrate 328 though solder bumps 304. The third die may be formed substantially of gallium arsenide, silicon on sapphire, or silicon germanium. The second die 310 forms a Base Band/Communication Processor 210 and mechanically couples to the first die 306 that includes a radio frequency integrated circuit (RFIC) 208. The first die 306 is electrically coupled to the substrate 328, often through solder bumps 308. For first die 306 sizes less than approximately 3.5 mm×3.5 mm underfill may often not be used. Larger first die 306 may utilize underfill. The second die 310 is electrically coupled to the substrate 328 through wire bonds 312. One method of mechanically coupling the first die 306 and second die 310 includes using an interface bonding agent 314, for example an epoxy. Many interface bonding agents 314 other than epoxy are known, e.g., RTV rubbers. The package 300 includes an antenna 204 formed of a copper stud 322 that couples to a package cover 334 that may act also as a heat spreader. Also included in the embodiment illustrated by FIG. 3 is a fourth die 316 on which is formed memory 210. The fourth die 316 couples to the circuitry of the second die 310 through a direct chip attach formed of solder bumps 318 and underfill 320. Some embodiments of underfill 320 may include an adhesive tape or epoxy. Passive components 330 and 332, such as inductor based components used for tuning, may be located at convenient locations on the substrate 328 if they are not included in the die 306 including the RFIC 208. The passive components 330 and 332 may include high speed switching components formed on depleted CMOS devices, thereby enabling reconfigurable adaptive passive circuits. The package substrate 328 may have solder mask defined pads for surface mount components, and immersion gold plating may be used on the pads.

The embodiment of the package 300 shown includes an array of solder balls 326 that may be used to electrically and mechanically couple the package 300 to a printed circuit board (not shown). Some of the solder balls 326 may be arranged in groups 324 that will collapse and coalesce during reflow, and form a large area connection convenient for grounding the package 300. FIG. 4 illustrates a substrate 402 of a package 400 with an array of signal solder balls 404 and an array of ground solder balls 408. The signal solder balls are distributed using a ball to ball pitch 406 that maintains the integrity of each solder ball 404. The solder balls 408 used for grounding are distributed with a narrower pitch 410 such that on reflow the balls coalesce to form a larger area connection. The embodiment shown by FIG. 4 includes solder balls 412 that may be used for power, ground, additional signals, or merely additional structural support without any electrical connectivity. A printed circuit board 414 may include arrays of exposed pads 416 and 418 similar to the arrays of solder balls. For example, the pitch 420 between exposed pads for the signals may be substantially similar to the pitch 406 for the signal solder balls 404. Ground pads 418 may be a single large area of exposed metal, or an array of large exposed areas, similar to those shown. The substrate 414 may have outer metal layer thicknesses of approximately 35 μm and inner metal layer thickness ranging from approximately 60 μm to 150 μm.

A Single Package Radio Transceiver Assembly Method

FIG. 5 illustrates an exemplary method of integrating a multiple die in a single integrated circuit package. The method illustrated may be used to package a combination of die wherein some of the die forming the radio transceiver are stacked and form a three dimensional integration. For example, the method of FIG. 5 includes soldering a first die to a package substrate having a layer of electrical traces and another layer of dielectric material 502. A method similar to one illustrated by FIG. 5 also includes mechanically coupling a second die to the first 504. To achieve a functional die stack, wire bonds electrically couple the second die to the package substrate 506.

As mentioned, the method illustrated by FIG. 5 results in a substantially integrated radio frequency transceiver. The method illustrated by FIG. 5 may be used to form a radio frequency transceiver capable of communicating according to any of a multitude of wireless standards that cover operation of networks ranging from personal area networks or local area networks to metropolitan area networks or wide area networks. Consequently, FIG. 5 illustrates forming an antenna electrically coupled to the substrate 508 and soldering a third die to the substrate, wherein the antenna, first, second, and third die substantially form a radio transceiver 510. The third die will often be substantially formed of gallium arsenide, silicon on sapphire, or silicon germanium, although other materials may often work as well.

In a radio frequency transceiver of the type whose assembly process is illustrated by FIG. 5, the second die substantially forms the often heavily computational, digital circuits of a base band communication processor. Some embodiments of a radio frequency transceiver couple memory to the digital circuits of the base band communication processor. Some of those embodiments may use a separate die for the memory and couple the memory die to the second die that substantially includes the digital circuits of the base band communications processor. A method of assembly, as illustrated by FIG. 5, may couple the memory die to the second die prior to mechanically coupling the second die to the first die 512.

Further, radio frequency transceivers may often benefit from grounding through large area electrical ground connections. As described above, such connections may form when two or more solder balls collapse and coalesce during reflow and form an electrical connection with larger cross-sectional area than a single constituent solder ball 514.

A System Embodiment that Includes a Single Package Radio Transceiver

FIG. 6 illustrates a schematic representation of one of many possible systems 60 that incorporate an embodiment of a single package radio transceiver 600. In an embodiment, the package containing a radio frequency transceiver 600 may be an embodiment similar to that described in relation to FIG. 3. In another embodiment, the package 600 may also be coupled to a sub assembly that includes a microprocessor. In a further alternate embodiment, the integrated circuit package may be coupled to a subassembly that includes an application specific integrated circuit (ASIC). Integrated circuits found in chipsets (e.g., graphics, sound, and control chipsets) or memory may also be packaged in accordance with embodiments described in relation to a microprocessor and ASIC, above.

For an embodiment similar to that depicted in FIG. 6, the system 60 may also include a main memory 602, a graphics processor 604, a mass storage device 606, and an input/output module 608 coupled to each other by way of a bus 610, as shown. Examples of the memory 602 include but are not limited to static random access memory (SRAM) and dynamic random access memory (DRAM). Examples of the mass storage device 606 include but are not limited to a hard disk drive, a flash drive, a compact disk drive (CD), a digital versatile disk drive (DVD), and so forth. Examples of the input/output modules 608 include but are not limited to a keyboard, cursor control devices, a display, a network interface, and so forth. Examples of the bus 610 include but are not limited to a peripheral control interface (PCI) bus, PCI Express bus, Industry Standard Architecture (ISA) bus, and so forth. In various embodiments, the system 60 may be a wireless mobile phone, a personal digital assistant, a pocket PC, a tablet PC, a notebook PC, a desktop computer, a set-top box, an audio/video controller, a DVD player, a network router, a network switching device, a hand-held device, or a server.

Although specific embodiments have been illustrated and described herein for purposes of description of an embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve similar purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. For example, a processor and chipset may be integrated within a single package according to the package embodiments illustrated by the figures and described above, and claimed below. Alternatively, chipsets and memory may similarly be integrated, as may be graphics components and memory components.

Those with skill in the art will readily appreciate that the description above and claims below may be implemented using a very wide variety of embodiments. This detailed description is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof. 

1. An integrated circuit package comprising: a substrate including a first layer with electrical traces that partially form an integrated circuit on the substrate and a second layer substantially formed of dielectric material; a first plurality of solder regions at a bottom of the second layer, each region having a cross-sectional area less than a first particular value; a second plurality of solder regions at the bottom of the second layer to provide grounding for a radio transceiver, each region having a cross-sectional area of a value that is different than the first particular value; a first die, including a first integrated circuit, with an array of solder bumps on a first side of the die wherein the solder bumps couple the first integrated circuit to the substrate; a second die, including a second integrated circuit electrically coupled through wire bonds to the integrated circuit on the substrate, mechanically coupled to a second side of the first die that is substantially parallel to the first side of the first die, such that the first die is disposed between the substrate and the second die an antenna electrically coupled to the integrated circuit on the substrate; a third die, including a third integrated circuit, electrically coupled to the second integrated circuit by means of an array of solder bumps, wherein the antenna and the first, the second and the third integrated circuits substantially form the radio transceiver; and the value of each of the second plurality of solder regions after reflow exceeds the first particular value when the substrate is soldered on a printed circuit board.
 2. The integrated circuit package of claim 1 wherein the second integrated circuit further comprises a base band communication processor.
 3. The integrated circuit package of claim 1 further comprising the third die, including the third integrated circuit forming a memory device, electrically coupled to the second integrated circuit through the respective solder bumps that connect an active side of the third die to an active side of the second die.
 4. The integrated circuit package of claim 1 wherein the first integrated circuit further comprises a radio frequency integrated circuit and a mixed signal processor.
 5. The integrated circuit package of claim 1 wherein the radio frequency transceiver is capable of communicating according to a wireless standard used substantially for a selected one of the group consisting of a personal area network, a local area network, a metropolitan area network, a wide area network, and a combination thereof.
 6. The integrated circuit package of claim 1, wherein the third die is formed substantially of a selected one chosen from the group consisting of gallium arsenide, silicon on sapphire, and silicon germanium. 